Comment by jefc1111

I like these. I have one which gives you a little HTML playground. It's in my favourites and I use it quite a lot for jotting things down.

data:text/html,<pre onkeyup="(function(d,t){d[t]('iframe')[0].contentDocument.body.innerHTML = d[t]('pre')[0].textContent;})(document,'getElementsByTagName')" style="width:100%;height:48%;white-space:pre-wrap;overflow:auto;padding:2px" contenteditable></pre><iframe style="width:100%;height:48%">